From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Emanuel Berg Newsgroups: gmane.emacs.help Subject: Re: Easy to add with push but not to the end of a list Date: Mon, 28 Nov 2022 23:50:00 +0100 Message-ID: <871qpm7kyv.fsf@dataswamp.org> References: <878rju96i5.fsf@dataswamp.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="23228"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:+RKLwDQMmvEgv+/BL67klojVzQ4= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Wed Nov 30 14:46:49 2022 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1p0NQH-0005p3-Hi for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 30 Nov 2022 14:46:49 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p0NQA-00062H-P7; Wed, 30 Nov 2022 08:46:42 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ozn1n-0001ig-6c for help-gnu-emacs@gnu.org; Mon, 28 Nov 2022 17:55:08 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ozn1k-0001zj-UL for help-gnu-emacs@gnu.org; Mon, 28 Nov 2022 17:55:06 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1ozn1i-0002Ng-8m for help-gnu-emacs@gnu.org; Mon, 28 Nov 2022 23:55:02 +0100 X-Injected-Via-Gmane: http://gmane.org/ Mail-Followup-To: help-gnu-emacs@gnu.org Mail-Copies-To: never Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -15 X-Spam_score: -1.6 X-Spam_bar: - X-Spam_report: (-1.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Wed, 30 Nov 2022 08:46:41 -0500 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:141258 Archived-At: Heime wrote: >>> Although it is easy to add to a list using push, it >>> currently looks hideous to be able to add to the end of >>> a list. >> >> That's because adding to the end of a Lisp list is >> a bad idea. > > The bad idea comment disregards necessity. Okay NOW it works ... (defmacro push-last (elem lst) (if (and (symbolp lst) (not (symbol-value lst)) ) (list 'setq lst `(list ,elem)) (list 'nconc lst `(list ,elem)) )) ;; (setq lst ()) ; () ;; (push-last 1 lst) ; (1) ;; (push-last 1 lst) ; (1 1) ;; lst ; (1 1) ;; ;; (setq lst '(1 2 3 4)) ; (1 2 3 4) ;; (push-last 5 lst) ; (1 2 3 4 5) ;; (push-last 5 lst) ; (1 2 3 4 5) ;; lst ; (1 2 3 4 5 5) -- underground experts united https://dataswamp.org/~incal